Performance with MAX clause

Question

I have performance issue with this query. the table is huge it has 10M rows. can we achive the same result below by rewriting in some other way?
the column px_date, px_type and px_active are indexed ,, composite index
SELECT MAX(GP.PX_DATE) PX_DATE,
                  GP.PRICING_SECURITY_ID,
                  GP.PX_ISO_CCY
               FROM price_today GP
               WHERE GP.PX_DATE <= '28-SEP-07'
               AND GP.PX_TYPE = 'PS1'
               AND GP.PX_ACTIVE = 'A'
               GROUP BY GP.PRICING_SECURITY_ID, GP.PX_ISO_CCY

Answer 1

the column px_date, px_type and px_active are indexed
,, composite indextry to create another composite index with a different column oder. Check the excecution plan to see if the index is used. If not try to force usage of the index
with a hint.
The column order should include the most restrictive column in the first place.
px_type, px_active, px_date
Also possible could be to create a separte index for each column. But I wouldn't like it. Note that in 11g you can collect combined statistics for all three columns. This is not possible in previous versions and might therefore require an index hint for best performace.